1

Orthomosaics generated by the processing of images obtained by UAV flights may often result in very heavy files that can take a long time to do simple tasks, just like to zoom on a specific region of the image.

I read about virtual raster and pyramid creation to deal with multiple raster files (on this topic -> Handling Many Raster Files in QGIS?) but I'm not sure if is this the best way to handle heavy raster files in QGIS?

  • 2
    Did you try pyramids and/or virtual rasters and what were your results? – Matthias Kuhn Dec 12 '16 at 13:00
  • Good general information in the presentation slideshare.net/geosolutions/geoserver-on-steroids-foss4g-2015. Same principles are valid for desktop usage 1) Make the original images tiled 2) Create overviews 3) Combine images into mosaic 4) If mosaic is very large use system like ImagePyramid. Converting the imagery into GeoPackage raster is a good alternative for QGIS. Use gdal_translate and don't forget to create overviews with gdaladdo. – user30184 Dec 12 '16 at 13:16
  • I tried the pyramid creation on an orthomosaic that covers about 600 ha with a resolution of ~6cm/pixel and it helped a lot in terms of panning, zooming, etc. As it was the first time i used the pyramid creation i wasn't sure if it was correct thing to do and neither if there are another paths i could follow. I'll follow these instructions and see if gets me to better results. The orthomosaic i'll use to work as soon as we finish the field work will cover about 4600 ha with a resolution of ~10cm/pixel. – EcoTerra Mapeamentos Dec 12 '16 at 13:34
  • An area of 4600 hectares @ 10cm per pixel is indeed "heavy". I'd definitely consider not creating a single mosaic build a VRT as suggested in the linked answer. If you must mosiac the entire image first (for whatever reason), then you can always tile it and then build pyramids for sure. – MappaGnosis Dec 12 '16 at 17:04
  • GDAL VRT is not especially fast when it has hundreds or thousands of images but make a test. Creating a VRT is cheap. – user30184 Dec 12 '16 at 21:05

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.